This invention relates to an adjustable arm and in particular to an arm consisting of a plurality of arm sections disposed in end to end relation with adjacent arm sections interconnected for angular movement therebetween about at least one axis and incorporating means for locking the interconnection.
Adjustable arms of the type to which this invention relates are well-known. For example in U.S. Pat. No. 3,278,207 there is a disclosure of a support structure having at least three joints which can be locked and unlocked simultaneously by a single movement, the structure involving at least one split ball joint. It has now been found that a more effective locking of the ball joint can be achieved by utilising a ball and socket joint, providing a locking member slidably mounted in a recess in the ball so that one end projects from the ball and bears against the socket, and applying a compressive force to the locking member by means of a compression member.